Subject: [Sigtran] Loadsharing based on SLS in SUA

From: [email-masked]
Date: Thu, 15 Dec 2005 15:04:01 +0530

Hi,

Since SLS parameter is not available in SUA layer, and Sequence Control
has a one to one mapping with SLS,  is Sequence control used for
"loadsharing based on SLS" in SUA.

>From RFC Q.714

In protocol class 1, the features of class 0 are complemented by an
additional feature (i.e. the

sequence control parameter contained in the N-UNITDATA request
primitive) which allows the

higher layer to indicate to the SCCP that a given stream of NSDUs shall
be delivered in-sequence.

The Signalling Link Selection (SLS) parameter in the MTP-TRANSFER
request primitive is chosen

by the originating SCCP based on the value of the sequence control
parameter. The SLS shall be

identical for a stream of NSDUs with the same sequence control
parameter. The MTP then encodes

the Signalling Link Selection (SLS) field in the routing label of MTP
messages relating to such

NSDUs, so that their sequence is, under normal conditions, maintained by
the MTP and SCCP. With

the above constraints, the SCCP and MTP together ensure in-sequence
delivery to the user. Thus,

this protocol class corresponds to an enhanced connectionless service,
where an additional

in-sequence delivery feature is included.

>From RFC 3868

The field is coded with the value of the sequence control parameter

associated with a group of messages and are chosen so as to ensure

proper loadsharing of message groups over SLS values while ensuring

that sequence control values within message groups have the sequence

control value coded with the same value as the initial message of the

message group.

Regards

Amrita Garg

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---

From: "Brian F. G. Bidulock" <[email-masked]>
Date: Thu, 15 Dec 2005 04:53:18 -0700

amrita.garg,

Yes, but sequence control does not have a one to one mapping to SLS: it
has a many to one mapping.

--brian

[email-masked] wrote:                                   (Thu, 15 Dec 2005 15:04:01)
> 
>    Hi,
> 
> 
>    Since  SLS  parameter  is  not  available  in  SUA layer, and Sequence
>    Control  has  a one to one mapping with SLS,  is Sequence control used
>    for "loadsharing based on SLS" in SUA.
> 
> 
> 
>    From RFC Q.714
> 
>    higher  layer  to  indicate  to  the SCCP that a given stream of NSDUs
>    shall be delivered in-sequence.
> 
>    NSDUs,  so that their sequence is, under normal conditions, maintained
>    by the MTP and SCCP. With
> 

-- 
Brian F. G. Bidulock
[email-masked]
http://www.openss7.org/